1. Field of the Invention
The present invention generally relates to the field of semiconductors devices, and more particularly to a method for fabricating a semiconductor device having memory devices.
2. Description of the Prior Art
A flash memory is a non-volatile memory, which can preserve data within the memory even when an external power supply is off. Recently, since flash memories are re-writable and re-erasable, they have been widely utilized in the electrical products, such as mobile phones, digital cameras, video players, personal digital assistants (PDA) or systems on a chip (SOC).
Generally, a flash memory is composed of several flash memory cells. Each of the flash memory cells may include at least a control gate (CG) and a select gate (SG) disposed on a substrate. Precisely, in order to enhance the performance of the flash memory, there may be a metal silicide layer disposed at the surface of the substrate between the control gate and the select gate. However, since an electron trapping layer, such as a silicon oxide-silicon nitride-silicon oxide (ONO) layer, of the control gate often extends from the bottom of the control gate to the space between the control gate and the select gate, metal elements used to form the metal silicide layer are often blocked by the electron trapping layer during the formation of the metal silicide layer. Therefore, the metal silicide layer is usually non-uniformly distributed at the surface of the substrate between the control gate and the select gate. Consequently, how to overcome this problem is still an important issue in the field, in order to improve the performances of the flash memory cell.